Avalanche Forecast
Regions: Kakwa, McGregor, North Rockies, Pine Pass, Tumbler.
Make observations of recent wind transport to navigate around wind slabs produced by Saturday's storm. North through east aspects should be most problematic but older, more stubborn slabs from the previous wind event may still react to human or machine triggers on south aspects.
Confidence
Moderate
Avalanche Summary
Observations of new avalanche activity from Saturday and Sunday aren't in yet but we anticipate some degree of a natural avalanche cycle took place in areas like Pine Pass, where up to 30 cm of new snow fell and active human triggering conditions where accumulations were more limited.
Earlier in the week there was evidence of deep persistent slab activity that likely occurred during last weekend's storm with avalanches up to size 3.5. While we currently expect the deep weak layer to be dormant, riders should continue to avoid steep, thin, rocky slopes where triggering a deep persistent avalanche would be most likely, particularly near alpine ridgelines.
Looking forward, we anticipate that new wind slabs will form Saturday night which will be sensitive to human triggering on Sunday.
Snowpack Summary
Up to 30 cm of new snow fell in Pine Pass during Saturday's storm, with closer to 10-15 cm elsewhere in the region.
The snow overlies older wind slabs that formed between Tuesday and Friday as well as heavy wind effect from strong northeast wind during this period. This means a mix of stubborn old and reactive new wind slabs may now be found on all aspects.
The middle of the snowpack is generally strong.
A weak layer of large and weak facets is found near the base of the snowpack. The layer is currently dormant, except perhaps in very steep alpine terrain that is inherently shallow. Riders should continue to avoid thin, rocky terrain where the likelihood of triggering this layer is higher.
Weather Summary
Sunday night
Cloudy with scattered flurries bringing less than 5 cm of new snow. Light southwest winds.
Monday
Mainly cloudy with isolated flurries. Light south winds. Treeline high temperatures around -13 °C.
Tuesday
Mainly cloudy. Light east winds. Treeline high temperatures around -13 °C.
Wednesday
Increasing cloud and flurries with a trace of new snow by end of day, continuing overnight. Winds becoming strong southwest. Treeline high temperatures around -12.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Expect slab conditions to change drastically as you move into wind exposed terrain.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Avalanche Problems
Wind Slabs
A mix of older, more stubborn wind slabs on south-facing terrain and newer, more reactive slabs on north through east aspects are now scattered around the region as a result of recent northerly winds transitioning back to a southwest flow during Saturday's storm. Larger, more reactive slabs should be expected in the Pine Pass area, a snowfall hotspot in the storm.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2